Providing cooling holes in combustion chamber liners and shield heat liners of gas turbine engines usually requires drilling hundreds of holes with variable inclination angles. Known processes of drilling such holes include the use of a pulsed laser in a drilling machine having five degrees of freedom where the worktable receiving the workpiece and the laser head are driven by ball screws. Generally, the table is translated along and rotated about perpendicular horizontal axes (x,y) and the laser head is translated along a vertical axis (z).
The limited capabilities of the feed drives and the dynamic constraints due to the high moving mass and inertia of such a drilling machine limits the linear and angular accelerations of the relative movement between the laser head and the worktable. Thus, the positioning between two consecutive holes on the workpiece usually takes more time than the time between two pulsations of the pulsed laser. Accordingly, the laser shutter must be closed and opened each time the machine moves from one hole to the next As a result, a major part of the cycle time between consecutive holes is spent in positioning the worktable and/or laser head and opening/closing the laser shutter, which largely increases the duration of the drilling process.
Accordingly, there is a need to provide an improved high speed laser drilling machine and method.